In vitro head-to-head comparison of the durability, versatility and efficacy of the NGage and novel Dakota stone retrieval baskets

Abstract

Background: To compare head to head two end-engaging nitinol stone retrieval devices available to urologists, in terms of durability, versatility and efficacy.

Methods: For durability testing, 30 NGage and Dakota baskets were cycled 20 times between grasping and releasing synthetic stone models and evaluated for damage or device failure. For versatility and efficacy testing, baskets were assessed in their ability to capture and release stone models from 1 to 11 mm. Each stone was raised above the capture site and the basket was opened to passively release the stone. If the stone did not release, the basket handle was shaken and the OpenSure feature employed if needed. Manual release was used as a last resort.

Results: Durability-the Cook NGage demonstrated a statistically significant increased rate of visible device breakdown (P=0.0046) in 8 of 30 (26.7%) devices vs. 0 of 30 Dakota devices, with mean damage at 13.5 cycles. Versatility and efficacy-both 8 mm baskets successfully captured stones from 1-8 mm. The Dakota more effectively released 7-8 mm stones (P<0.0001). NGage required manual release of 8 mm stones in 13 cases compared to none with Dakota. For 11 mm baskets, the Dakota released all stones up to 10 mm with simple opening, while the NGage released 10 of 15 (67%) of 9 mm stones and 1 of 15 (7%) of 10 mm stones by simple opening. For 11 mm stones, the Dakota captured 100% whereas NGage could not capture any.

Conclusions: Both baskets showed similar durability characteristics. The Dakota basket more effectively captured and released stones over 7 mm, as compared to the NGage basket. The OpenSure aspect conferred an advantage in handling and release of larger stones. These in vitro results demonstrate potential versatility, durability and efficacy of the Dakota basket.

Keywords: Kidney stone; durability; nitinol; stone basket; tipless.

Figure 1

The two commercially available end-engaging Nitinol stone retrieval devices, NGage™ (Cook Urological Inc., Bloomington, IN, USA) and Dakota™ (Boston Scientific, Natick, MA, USA), hold stones like a basket but engage and release like a grasper. (A) Closeup of the NGage in open position; (B) opening of the Dakota at full deflection of the ureteroscope; (C,D) Dakota with OpenSure™ handle in normal open basket position (C) and with handle engaged in full open position (D).

Figure 2

Durability, versatility and efficacy testing. (A) The basket was passed through a simulated endoscopic working channel and cycled in grasping and releasing synthetic stones; (B) red arrows depict areas of visible basket breakdown in baskets inspected after repetitive use; (C) stone model showing 1 and 9 mm synthetic model stones.